Bumper fender assemblies are commonly used to protect docks and offshore platforms. Such assemblies typically employ a resiliently encased vertical cylinder which is mounted to a leg of the platform. Typically, the cylinder is encased by a series of stacked resilient cylindrical rings in the manner taught by U.S. Pat. Nos. 3,991,582 and 4,005,672. Heretofore, general maintenance requirements for bumper fendering assemblies have been difficult and time consuming. U.S. Pat. No. 4,005,672 represents an improvement over earlier marine fender designs wherein a main cylinder is supported at the lower extremity by a stab post and is removably connected at the upper extremity thereof to a energy absorbing cell type connection structure. Although somewhat improved, maintenance of bumper fender assemblies remains a difficult and time consuming problem because of the necessity for replacement of one or more of the plurality of damaged cushioning rings that surround the main cylinder. It is desirable, therefore, to provide a marine bumper or fender assembly having a shock resistant impacting portion which portion is simply and easily removable for repair or replacement of the resilient portion thereof.
It is also considered desirable to provide in addition to an impact cushioning portion, an energy absorbing portion that allows substantial transverse movement in the event the mechanism is required to absorb substantial energy. It is desirable, therefore, to provide a marine fender assembly having the capability of absorbing shock forces whether applied centrally or at the upper or lower portions of the fender structure.
Where energy absorbing cells (EAC) are utilized in marine fender assemblies with an elastomeric material being provided as the energy absorbing component, it is at times desirable to provide for resistance to light energy levels and at the same time provide effective resistance to perpendicular forces. At times design conditions require reduced reaction loads into the platform, and thus require a soft energy absorber. Where typical shock cells are employed it is generally considered impractical to provide energy absorbing cells having both of these capabilities.
It is an even further feature of this invention to provide a novel marine fender assembly having elastomer containing energy absorbing cells wherein the elastomer energy absorbing portion thereof is capable of providing reduced reaction loads while at the same time providing effective resistance to transverse forces of substantial magnitude, such as are typically induced when the marine fender is struck in such manner as to define a force vector in angular relation to the centroid of the energy absorbing cell.
It is also a feature of this invention to provide a novel marine fender mechanism wherein vertical force components acting on the energy absorbing members are effectively minimized.
Other and further objects, advantages and features of the invention will become obvious to one skilled in the art upon an understanding of the illustrative embodiments about to be described and various advantages, not referred to herein, will occur to one skilled in the art upon employment of the invention in practice.